Since life extending technologies may or may not yield ways to repair serious body damage, you should make sure to maintain parts that may not be fully repairable, like gums/teeth, knees/joints, neck/posture (vertebrae fusing), etc. Not sure what maintenance you can do about the eyes though (most people need reading glasses by mid/late-40's).

Let's suppose that real results come out of current research into NAD-boosting and other methods for reducing defects when cells split and for reducing senescence of cells. That would extend your potential lifetime but you can still die from accidents/violence, cancer, and diseases incl heart disease, so you need to take preventative measures for those factors.

David Sinclair suggests that you should cut sugar/desserts from your diet (because it encourages cell splitting), and reduce damage to your body, e.g. use sunscreen (because cell defects arise when repairing cell damage).

If humans could grow biblically old, like 600-900 years, one thing to consider is it's possible they might start looking like Ferengi, since cartilage just keeps growing.